Hello, I have a 94 jayco that developed a new problem that is causing me to rip my hair out. The 20 amp fuse that is inline coming off the positive terminal to ground blew out on us today. I have checked everything I can that I know of. Our 12v system is down, I checked dc across the battery, ground continuity, fuses, breakers all of it I can't find anything that would cause the fuses to arc the second they go back into the fuse holder. Edit: 24v to 12v because I'm an idiot.

I misspoke earlier I have a single deep draw 12v marine battery from positive to ground I have 12v neg to ground is 0 from positive terminal to battery side fuse holder is 12v to trailer side is 0. I have had it for a few months, everything was working perfectly until today it popped at can't figure out where the short is

There are a few cases where a positive ground is used, but an RV isn't one of them. And a ground is not normally fused either, though there is nothing wrong with that. The battery ground would require much more than a 20A fuse, though.

Check to see if there is another wire from the battery negative to the chassis. If so, that is your "ground" and the 20A wire is for something else. What is it connected to on the other end? It should NOT be the chassis or body of the RV.

Inside the battery compartment there is a row of screw studs booked to the metal frame 2 black wired come out of the body of the trailer and attach to it and the wire with the inline fuse go to it. The other wire from the positive goes back into the body.

I've been troubleshooting all morning and I have narrowed it down to a bad or wonky converted. Took the battery out and got it tested hooked it back up with no converter and everything worked fine. Hooked the converter back to it and the fuse instantly blew.

I misspoke earlier I have a single deep draw 12v marine battery from positive to ground I have 12v neg to ground is 0 from positive terminal to battery side fuse holder is 12v to trailer side is 0. I have had it for a few months, everything was working perfectly until today it popped at can't figure out where the short is

I'm confused....you said positive to battery side of fuse holder is 12V to ground. You said to the trailer side is zero. Is that with the fuse blown? A fuse is just a wire, so how can you have a different reading from the line to load side? I'm an electrician, so maybe my terminology is different, but...if you have a VOM, pull the fuse and measure load side resistance of the fuse holder to ground and also read it at the converter positive battery connection. To avoid blowing fuses, measure the positive terminal of the converter to the negative terminal. make sure your meter has the polarity correct. If it reads near zero ohms, you may just have a wiring problem in the converter. Pull all of the fuses and measure it again. If it changed, put the fuses back in one at a time to see if any cause the reading to drop. Basically, just try to narrow down what is causing the reading to be near zero. May save you from buying a new converter.

A trick to keep from repeatedly popping fuses while tracing down a short is to replace the fuse with a 12 volt light bulb. Put a pair of wires onto the bulb or use a lamp socket and connect them in place of the fuse.

While the short exists, the light bulb will glow at full brightress while limiting the short circuit current to a safe value. When you eliminate the short the light bulb will either go out or glow at reduced brightness, depending on what else is on the circuit.

You can get an arc regardless of which terminal is connected last; it's exactly the same connection?

As far as currect flow goes, most tech's, including me, were taught the negative to positive flow theory. But, if you ask a physicist he will swear it's positive to negative. It makes no practical difference for our purposes.

And we're not going to get into solid state components where holes flow instead of electrons.

Actually not trying to get to picky but electricity really flows from negative to positive.

LOL! Somebody was bound to bring that up, but it's irrelevant. The electrical potential (voltage) is considered to be from Positive to Negative, even though that's a design convention more than a physical fact about how the electrons actually move about. Some DC electrical devices don't care which pole is which, but the ones that do are designed based on the convention that flow is from positive to negative. If you try to switch the polarity, those devices won't work (led lighting is a common example).

And then there is the solid state logic stuff that Ernie mentioned. Let's not go there...

The fact of the matter is that electrons (electricity) flows from negative to Positive. Way back when, the founding fathers of electricity thought that electricity flowed from Positive to Negative. Later on, when it was discovered that electricity actually flowed from Negative to Positive the electrical geniuses at the time decided that for all intents and purposes, it didn't matter. It didn't matter because the formulas and practical applications were not affected in any way. Everything still worked just fine either way and so it was decided to stick with the existing convention rather than cause confusion. The physicists, mathematicians, electronics industries and all those otherwise involved in electricity understand this concept that electrons actually flow from neg to pos and so still stick to the original concept rather than change because it doesnt matter.

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TonyBRetired and full time living aboard our Denali 293RKS. Don't know much about RV"s in general and are still learning. First lesson learned is that dealerships are not responsible for anything and warranties can be used for toilet paper.

Ome way to isolate the problem would be to remove all the DC fuses. The install the main neg. to ground fuse. Ig the fuse pops, then the problem is with the main power cables. If it doesnt pop the main fuse, add one fuse at a time. When you hit the fuse that pops, that is the component where the problem exists.

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TonyBRetired and full time living aboard our Denali 293RKS. Don't know much about RV"s in general and are still learning. First lesson learned is that dealerships are not responsible for anything and warranties can be used for toilet paper.